Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754374AbcKUR0n (ORCPT ); Mon, 21 Nov 2016 12:26:43 -0500 Received: from fllnx210.ext.ti.com ([198.47.19.17]:46458 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753513AbcKUR0m (ORCPT ); Mon, 21 Nov 2016 12:26:42 -0500 Subject: Re: [PATCH] drm: tilcdc: reduce max_width for revision 1 To: Bartosz Golaszewski , Tomi Valkeinen , David Airlie , Kevin Hilman , Michael Turquette , Sekhar Nori References: <1479748590-3962-1-git-send-email-bgolaszewski@baylibre.com> <1479748590-3962-2-git-send-email-bgolaszewski@baylibre.com> CC: LKML , linux-drm , Peter Ujfalusi , arm-soc From: Jyri Sarha Message-ID: <2013ba47-e7e4-045e-0232-4ebd7450c3ad@ti.com> Date: Mon, 21 Nov 2016 19:26:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <1479748590-3962-2-git-send-email-bgolaszewski@baylibre.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1317 Lines: 41 On 11/21/16 19:16, Bartosz Golaszewski wrote: > It has been determined that the highest resolution supported correctly > by LCDC rev1 is 800x600. Reduce the max_width value for rev1 to 800 in > crtc_max_width(). > I don't think this is the right way to limit the supported video modes. There is technically there is no such limit, is there? If memory bandwidth is limiting the functionality of higher resolutions, you should use "max-bandwidth" tilcdc device-tree property [1]. Cheers, Jyri [1] In "Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt": Optional properties: - max-bandwidth: The maximum pixels per second that the memory interface / lcd controller combination can sustain > Signed-off-by: Bartosz Golaszewski > --- > drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > index dfe3dd0..9081de5 100644 > --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > @@ -683,7 +683,7 @@ int tilcdc_crtc_max_width(struct drm_crtc *crtc) > int max_width = 0; > > if (priv->rev == 1) > - max_width = 1024; > + max_width = 800; > else if (priv->rev == 2) > max_width = 2048; > >